1. Field of the Invention
The present invention relates to a piezoelectric member (electrostrictive member) element and a liquid discharge head comprising the element (hereinafter, also referred to as “ink-jet head”). In particular, the present invention relates to a piezoelectric member element that can be applied as a sensor, a transducer and an actuator, etc. In particular the present invention is preferable to MEMS elements and ink-jet heads that have been attracting attention in recent years. In addition, other than ink-jet devices, the present invention is applied to head for memory, optical shutter, etc., ultrasonic motor, speaker, and the like.
2. Related Background Art
As piezoelectric member element, in recent years, taking utilization of semiconductor process into consideration, the one with an element being produced on an Si substrate is developed. Therefore, methods of forming thin film such as sol-gel method, sputtering method, MO-CVD method and the like are being considered. In addition, in order to improve characteristics for piezoelectric member element, consideration on improvement of crystal properties of piezoelectric member film is being implemented as well.
In particular, it has been announced that directing piezoelectric member film such as PZT, etc. to (001) preferential orientation or (111) preferential orientation with an Si substrate having general-purpose (100) surface.
In addition, as piezoelectric member film, films directed to (110) preferential orientation are being considered, but in order to place a piezoelectric member film under crystal control to bring it into film forming onto an Si substrate, high temperature process under 700° C. or more will become necessary.
For example, those having utilized piezoelectric member film in (110) preferential orientation and described in Japanese Patent Application Laid-Open No. 2001-80995 and Japanese Patent Application Laid-Open No. 2003-179279 are known.
A piezoelectric member element described in Japanese Patent Application Laid-Open No. 2001-80995 is the one having used an Si substrate having (110) surface, and a method of laminating (110) preferential orientation onto the (110) surface, and, as in the prior art, a high temperature step will become necessary. Therefore, stress is left in the film to give rise to a problem in endurance.
In addition, a piezoelectric member element described in Japanese Patent Application Laid-Open No. 2003-179279 brings a buffer layer (YSZ, etc.) in (100) preferential orientation into film forming onto an Si substrate having (100) surface, and thereafter places it under crystal control to (110) in an electrode layer, but a high temperature step will become necessary to implement film forming of buffer layer as well to give rise to a problem as in case of piezoelectric member element described in Japanese Patent Application Laid-Open No. 2001-80995. In particular, in case of having utilized, as a vibration plate, a buffer layer to an ink-jet head, problems such as cracks in vibration plate, and delamination between an electrode layer and a buffer layer take place presumably due to influence of residual stress.